Scientists Work To Clone Livestock

Through biotechnology, animal scientists are working to create new types of livestock designed to produce more profit for farmers and higher quality meat and milk for consumers.

For a century or more, livestock breeders and animal scientists have bred the best male and female animals to produce better and higher-producing offspring. That has resulted in more and better beef, pork, lamb and dairy products.

Now selective breeding is giving way to the new science of biotechnology.

For example, at the University of Missouri at Columbia, animal scientists are working on a project to clone a whole herd of pigs.

The idea is to produce a herd of pigs that look alike and grow identically. If the project succeeds, the pigs would produce hams, pork chops, bacon, ribs and other cuts of pork that will also be alike.

Randall Prather, a University of Missouri animal scientist, said researchers may be able to clone pigs ``within a couple of years.``

``I`m confident we`ll be able to produce clones by transferring nuclei from 3- to 4-day-old embryos to unfertilized eggs,`` he said. ``Once the nuclei are put in the unfertilized egg, we`ll be able to reset the

reproduction clock.

``We can wait until the new embryos are about 5 to 6 days old and transfer them to surrogate mothers. Or we could pluck the nuclei from the very young embryos again and repeat the process indefinitely until we have as many clones as we like.``

Prather offers this scenario:

A farmer has produced an outstanding sow. He selects semen from an outstanding boar and fertilizes an egg from the sow.

Through nuclear transfer, 1,000 embryos could be produced, then frozen.

``We could just thaw a few embryos, implant them in surrogate sows, grow them out, and test rations on them,`` Prather said. ``Then, when we are satisfied these pigs have good genetic makeup and that we have developed good management techniques for growing these pigs, we could thaw out the rest of the embryos and produce a whole herd of uniform pigs.``

Prather said that even if the nuclear transfer technique fails to produce perfect clones, the procedure offers significant advantages to scientists.

He said it would allow them to study the interaction of the nucleus and other cell structures and ``help geneticists predict the offspring that will result with different genetic combinations.``

``Nuclear transfers are powerful tools to study reproductive development,`` he said. ``They will help us better understand reproduction so we can reduce embryonic losses, which now run 20 to 30 percent in pigs and cows.

``Also, cloning will help us produce genetically similar pigs for research purposes. Clones would be excellent to test feed rations, for example, because we`d know all differences in the pigs were influenced by environment, not genetics.

``That would also mean we would need fewer animals in research trials, because we wouldn`t have to repeat experiments over and over, trying to decide which factors were influenced by genetics and which were influenced by environment.``